Modular Structure of a Microporous MOF based on … · Modular Structure of a Microporous MOF based...

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Electronic Supplementary Information for:

Modular Structure of a Microporous MOF based on Cu2 Paddle-Wheels with High CO2 Selectivity

José M. Seco,a David Fairen-Jimenez,b,* Antonio J. Calahorro,c Laura Méndez-Liñán,c Manuel Pérez-Mendoza,c Nicola Casati,d Enrique Colacioc and Antonio Rodríguez-Diéguezc,*

aDepartamento de Química Aplicada, Facultad de Ciencias Químicas de San Sebastián, Universidad del

País Vasco, Paseo Manuel Lardizábal 3, 20008 San Sebastián, Spain. bDept. of Chemical Engineering & Biotechnology, University of Cambridge, Pembroke Street, Cambridge

CB2 3RA, United Kingdom.http://people.ds.cam.ac.uk/df334 cDepartamento de Química Inorgánica, Universidad de Granada, Av. Fuentenueva s/n, 18071, Granada,

Spain. dPaul Scherrer Institute, WLGA/229, Villigen PSI, 5232, Switzerland.

Email: David Fairen-Jimenez, [email protected], Antonio Rodríguez-Diéguez: [email protected]

Index S1. Experimental Section………………..…….…………..……………………………………S1

S2. Type I vs. Type III Deliverable Capacity……………..……………..…………….…….…S5

S3. Structural Information and Pore Size Distribution…………………...……….…….…...…S6

S4. Gas Adsorption Isotherms…………...……....………………………………..…………....S7

S5. High-Pressure X-Ray Diffraction Analysis ………………………………………..………S8

S6. References…………………………………….………………………………...…...……..S9

S1. Experimental Section Synthesis of [Cu2(glu)2(µ-bpp)]·2H2O (1).

The reaction in water solvent of the copper sulfate (0.25mmol, 0.0628 g), glutaric acid (0.25 mmol,

0.033 g), urea (0.872 mmol, 0.054 g) and 4,4'-trimethylene-dipyridine (0.25 mmol, 0.046 g) led to

a blue solution, which kept at room temperature for one week gave rise to green crystals of complex

1, which were filtered off and air-dried. Yield: 60%. Anal. Calc. for C23H26Cu2N2O8: C, 47.18; H,

4.48; N, 4.78. Experimental: C, 47.05; H, 4.61; N, 4.83.

Electronic Supplementary Material (ESI) for Chemical CommunicationsThis journal is © The Royal Society of Chemistry 2013

mailto:[email protected]

mailto:[email protected]

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Physical Measurements

Microanalysis of C, H and N were performed in a Fisons Instruments EA-1008 analyser. The

thermal behaviour of 1 was studied under an air flow in Shimadzu TGA-50 and Shimadzu DSC- 50

equipment, at heating rates of 20 ◦C min-1 and 10 ◦C min-1, respectively. IR spectra were recorded

on a ThermoNicolet IR 200 spectrometer using KBr pellets. All this equipment is sited at the Centre

of Scientific Instrumentation of the University of Granada.

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Figure S1. Thermogravimetric curve obtained for 1.

Single-Crystal Structure Determination.

Suitable crystals of 1 were mounted on a glass fibre and used for data collection on a Bruker AXS

APEX CCD area detector equipped with graphite monochromated Mo Kα radiation (λ = 0.71073

Å) by applying the ω-scan method. Lorentz-polarization and empirical absorption corrections were

applied. The structure was solved by direct methods and refined with full-matrix least-squares

calculations on F2 using the program SHELXS97.1 Anisotropic temperature factors were assigned

to all atoms except for hydrogen atoms, which are riding their parent atoms with an isotropic

temperature factor arbitrarily chosen as 1.2 times that of the respective parent. Attempts to identify

the solvent molecules failed in compound 1. Instead, a new set of F2 (hkl) values with the

contribution from solvent molecules withdrawn was obtained by the SQUEEZE procedure

implemented in PLATON-94.2 Several crystals of 1 were measured and the structure was solved

form the best data we were able to collect. Final R(F), wR(F2) and goodness of fit agreement

factors, details on the data collection and analysis can be found in crystal data. Selected bond

lengths and angles are given in Tables S1. CCDC reference number for the structure of 1 was

xxxxxx.


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Table S1. Selected Distances (Å) and Bond Angles (º) for compound 1

C2A N1A C6A 116.4(4) C2A N1A Cu1 120.8(3) C6A N1A Cu1 121.8(3) N1A C2A C3A 123.8(5) C2A C3A C4A 120.3(5) C3A C4A C5A 116.2(5) C3A C4A C7A 124.7(5) C5A C4A C7A 119.0(5) C6A C5A C4A 119.8(5) N1A C6A C5A 123.3(5) C4A C7A C8A 115.7(5) C7A C8A C7A 109.9(6) O1B C3B O2B 123.6(4) O1B C3B C4B 119.6(4) O2B C3B C4B 116.8(5) C3B C4B C5B 116.3(4) C4B C5B C6B 111.9(4) C7B C6B C5B 112.9(4) O9B C7B O8B 125.0(5) O9B C7B C6B 117.0(4)

N1A C2A 1.331(7) N1A C6A 1.340(6) N1A Cu1 2.161(4) C2A C3A 1.374(8) C3A C4A 1.383(8) C4A C5A 1.395(7) C4A C7A 1.512(7) C5A C6A 1.382(7) C7A C8A 1.519(6) C8A C7A 1.519(6) C3B O1B 1.257(6) C3B O2B 1.269(6) C3B C4B 1.482(7) C4B C5B 1.515(7) C5B C6B 1.534(6) C6B C7B 1.506(6) C7B O9B 1.240(6) C7B O8B 1.246(6) C7B C6B 1.506(6) O1B Cu1 1.976(3) O2B C3B 1.269(6) O2B Cu1 1.981(3) O8B Cu1 1.970(4) O9B C7B 1.240(6) O9B Cu1 1.985(4) Cu1 Cu1 2.6332(12)

O8B C7B C6B 118.1(4) C3B O1B Cu1 124.9(3) C3B O2B Cu1 123.3(3) C7B O8B Cu1 120.8(3) C7B O9B Cu1 126.0(3) O8B Cu1 O1B 91.09(17) O8B Cu1 O2B 87.62(16) O1B Cu1 O2B 168.17(14) O8B Cu1 O9B 167.41(14) O1B Cu1 O9B 89.27(16) O2B Cu1 O9B 89.46(15) O8B Cu1 N1A 102.41(15) O1B Cu1 N1A 96.39(14) O2B Cu1 N1A 95.38(14) O9B Cu1 N1A 90.05(15) O8B Cu1 Cu1 86.27(11) O1B Cu1 Cu1 83.64(10) O2B Cu1 Cu1 84.54(10) O9B Cu1 Cu1 81.26(11) N1A Cu1 Cu1 171.31(11)

Gas Adsorption Isotherms

Volumetric N2 gas adsorption isotherms were undertaken using a Micromeritics Instrument

Corporation (Norcross, Georgia, USA) ASAP 2020 system. Approximately 300-500 mg of the

corresponding solid product was transferred to a preweighed sample tube and evacuated under

dynamic vacuum at 150 °C on the gas adsorption apparatus until the outgas rate was <5 μmHg. The

sample tube was reweighed to obtain a consistent mass for the degassed modified product. High-

pressure adsorption isotherms of H2 at 77 K and CH4 and CO2 at 273 K were determined using a

bench-scale volumetric adsorption instrument equipped with two Baratron absolute pressure

transducers (MKS type 627B). Their pressure range span from 0 to 1.33 bar and from 0 to 33.33

bar, respectively. The reading accuracy was 0.05% of the usable measurement range. Prior to all

the measurements, samples were degassed at 425 K for 12 h. All gases used were of 99.999%

purity. Helium was used for the dead volume determination.


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Gas Adsorption Simulations and Computational Structural Characterization

The adsorption of CO2 was investigated using grand canonical Monte Carlo (GCMC) simulations,

performed with the in-house multi-purpose code RASPA.3 We used a rigid atomistic model for 1, in

which the framework atoms were kept fixed at their crystallographic positions. Solid-fluid and

fluid-fluid interactions were calculated using a Lennard-Jones (LJ) + Coulomb potential. LJ

parameters for the framework atoms were taken from the Universal Force Field (UFF),4 the CO2,

LJ parameters from the TraPPE force field.5 Lorentz-Berthelot mixing rules were used for all cross

terms, and LJ interactions beyond 12 Å were neglected. Coulombic interactions were modelled by

placing partial charges on the framework atoms. The partial charges were calculated using an

extended charge equilibration method,6 and the long-range electrostatic interactions were calculated

using the Ewald summation method. 6·104 Monte Carlo equilibration cycles were performed plus

4·104 production cycles to calculate the ensemble averages. In one cycle, an average of N moves

were performed, where N is the number of molecules in the system (which fluctuates in GCMC).

Monte Carlo moves used with equal probability were translation, rotation, insertion, deletion, and

random reinsertion of an existing molecule at a new position. To calculate the gas-phase fugacity,

we used the Peng-Robinson (PR) equation of state (EOS)7.

Table S2. Lennard-Jones parameters for framework atoms and the gas molecules.

σ [Å] ε/k [K] q [e] C 3.431 52.838 N 3.261 34.722 O 3.119 30.192 H 2.571 22.142 Cu 3.114 62.397

C_CO2 2.800 27.000 +0.70 O_CO2 3.050 79.000 -0.35

The pore volume, used to compute excess adsorption from the simulated absolute adsorption,

was obtained using a Widom particle insertion method, by probing the structure with a helium

molecule at room temperature, recording a large number of random points not overlapping the van

der Waals volume of the framework.8 The pore size distributions was calculated using the method

of Gelb and Gubbins,9 where the largest sphere that can fit in a random point within a structure

without overlapping the van der Waals surface of the framework is recorded for a large number of

random points.


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S2. Type I vs. Type III Deliverable Capacity

Figure S2. Representation of Type I (left) and Type III (right) ideal adsorption isotherms. Blue arrows represent the deliverable capacity, i.e. the difference between the amount adsorbed at the maximum adsorption pressure and the amount adsorbed at the regeneration pressure,

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S3. Structural Information and Pore Size Distribution

Figure S3. Comparison between the MOF structures (left) 1 and (right) 210, along the (top) c and (bottom) b axis. The different molecular fragments have been indicated in red and green for clarity. Note the different arrangement of the bpp ligands based in the tilt of the pyridyl fragments respect to the propane chain that interconnects them.

Figure S4. Comparison of experimental XRD pattern (black line) with single-crystal structures (left), and pore size distribution (PSD) (right). Red line represents single-crystal 1, and blue line single-crystal 2.

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S4. Gas Adsorption Isotherms

Figure S5. Comparison between the experimental CO2 adsorption isotherms on structures 1 and 2 at two different temperatures. Blue diamonds, structure 1 at 273 K; red triangles, structure 2 at 273 K; purple squares, structure 2 at 196 K. (Left) and (right) shows different pressure ranges. Differences between 1 and 2 are related to the shape of the isotherms: i) The CO2 adsorption capacity of structure 1 up to 2 bar and 273 K is 0.01 wt%. A small plateau exists between 2-10 bar, with an uptake of ca. 1 wt. %. Both amounts are almost negligible compared with the 15 wt. % uptake obtained at 30 bar. ii) Structure 2 adsorbs ca. 11 wt. % at 1 bar and 273 K. In addition, the adsorption at lower temperature (196 K) and 1 bar (i.e. P/P0 ~ 0.5, where the whole microporosity should be saturated) increments the uptake up to 19.6 wt.%). The isotherms on 2 keep a Type I shape in all the temperature range (196 – 298 K).

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Figure S6. CO2 experimental, red circles, and simulated, black triangles, adsorption isotherms on 1 at 273 K. The simulated isotherm is able to provide a good estimation of the CO2 capacity of the material (ca. 23 wt. %). Note the big differences at lower pressure where the simulated data overpredict the experimental amount adsorbed.

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S5. High-Pressure X-Ray Diffraction

High pressure single crystal study was undertaken using a custom made Diamond Anvil Cell

equipped with 0.5 mm culets and a ~40° opening. A small crystal of the sample was loaded in the

pre-pressed and drilled steel gasket along with a methanol-ethanol mixture (4:1) and a small ruby

sphere for pressure calibration. Data were collected using a single phi scan in the Extreme

conditions beamline at Diamond Light Source, using a focused beam of 40 keV as defined by a 20

µm pinhole. Short acquisitions were performed to avoid large radiation damage, anyway visible at

the end of the experiment in the form of a brown spot in the center of the crystal. Data were

collected using an Agilent Atlas CCD calibrated with a NIST ruby sphere and integrated using the

Crysalis package and its high pressure dedicated abilities11. Diamond overlapping peaks were

masked out of the integration. Despite attempts no lower or higher symmetry were identified for the

given datasets up to 4.5 GPa. The known structure was used for refinement with SHELXL97.i Due

to the small amount of data and their low intrinsic quality aromatic rings were constrained using the

AFIX66 routine and other C-C and C-O distances restrained to 1.54 and 1.25 Å respectively. The

squeeze routine was applied to correct the intensities from the disorder solvent.

Figure 7. The ambient pressure structure of 1 (left) with arrows indicating the deformation modes. On the right, the resulting structure at 4.5 GPa.


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S7. References 1.- G. M. Sheldrick, SHELX97, University of Göttingen, Göttingen, Germany, 1997. 2.- A. L. Spek, PLATON-94 (V-101094), A multipurpose Crystallographic Tool, University of Utrecht, The Netherlands, 1994. 3.- (a) Dubbeldam, D.; Calero, S.; Ellis, D. E.; Snurr, R. Q. RASPA 1.0; Northwestern University: Evanston, IL, 2008; (b) D. Frenkel and B. Smit, Understanding Molecular Simulations: From Algorithms to Applications, 2nd ed., Academic Press, San Diego, 2002. 4.- A. K. Rappé, C. J. Casewit, K. S. Colwell, W. A. G. III and W. M. Skiff, J. Am. Chem. Soc., 1992, 114, 10024-10035 5.- M. G. Martin and J. I. Siepmann, J. Phys. Chem. B, 1998, 102, 2569 6.- C.E. Wilmer, K.C. Kim and R.Q. Snurr. J. Phys. Chem. Lett., 2012, 3, pp 2506–2511. 7.- Reid, R. C.; Prausnitz, J. M.; Poling, B. E. The Properties of Gases and Liquids, 4th ed.; McGraw-Hill: New York, 1987. 8.- (a) A. Leach, Molecular modelling : principles and applications, Pearson Prentice Hall, 2001.; (b) A. L. Myers and P. A. Monson, Langmuir, 2002, 18, 10261. 9.- L. D. Gelb and K. E. Gubbins, Langmuir, 1998, 15, 305-308. 10.- I.H. Hwang, J.M. Bae, W.-S. Kim, Y.D. Jo, C. Kim, Y. Kim, S.-J. Kim and S. Huh, Dalton Trans., 2012, 41, 12759. 11.- Oxford Diffraction (2006). Oxford Diffraction Ltd., Abingdon, England.


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